Dresden 2017 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 56: Posters - Granular and Particulate Matter
DY 56.8: Poster
Donnerstag, 23. März 2017, 17:00–19:30, P1A
Coarsening dynamics of ferromagnetic networks: experimental results and simulations — Armin Kögel1, •Tom Dumont1, Elena Pyanzina2, Sofia Kantorovich3, and Reinhard Richter1 — 1Experimentalphysik 5, University of Bayreuth, 95440 Bayreuth, Germany — 2Ural Federal University, Lenin av. 51, Ekaterinburg, 620000, Russia — 3University of Vienna, Sensengasse 8, Vienna, 1090, Austria
We investigate the phase separation of a shaken mixture of glass and magnetized steel spheres after a quench of the shaker amplitude. Then transient networks of the magnetic dipoles emerge in the experiment. We characterize the networks by the distribution of its number of neighbours, and its number of loops. For the emerging network clusters we estimate the number of spheres, the gyration radii, and the characteristic path lengths. We find that all three quantities follow a log-normal distribution function. Moreover, we study the temporal evolution of the mean number of neighbours and of the efficiency of the networks. We observe a sudden increase and than a moderate growth of both order parameters. This two distinct time scales are indicating an elastic and an hydrodynamic regime of the viscoelastic phase separation predicted by H. Tanaka (2000) for dynamically asymmetric mixtures. Eventually we use a simple simulation approach to understand the influence of the nonmagnetic spheres on the cluster structures formed by magnetic dipolar particles in quasi 2 dimensions. Not aiming at describing the experimental results we rather use the simulation approach to define the key interactions in the experimental system.